全文获取类型
收费全文 | 2252篇 |
免费 | 140篇 |
出版年
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 10篇 |
2019年 | 23篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 25篇 |
2015年 | 33篇 |
2014年 | 50篇 |
2013年 | 127篇 |
2012年 | 88篇 |
2011年 | 77篇 |
2010年 | 53篇 |
2009年 | 60篇 |
2008年 | 109篇 |
2007年 | 117篇 |
2006年 | 118篇 |
2005年 | 124篇 |
2004年 | 104篇 |
2003年 | 97篇 |
2002年 | 100篇 |
2001年 | 96篇 |
2000年 | 86篇 |
1999年 | 84篇 |
1998年 | 27篇 |
1997年 | 20篇 |
1996年 | 15篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 23篇 |
1992年 | 49篇 |
1991年 | 57篇 |
1990年 | 54篇 |
1989年 | 54篇 |
1988年 | 56篇 |
1987年 | 41篇 |
1986年 | 42篇 |
1985年 | 45篇 |
1984年 | 25篇 |
1983年 | 28篇 |
1982年 | 21篇 |
1981年 | 17篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1971年 | 8篇 |
排序方式: 共有2392条查询结果,搜索用时 15 毫秒
121.
122.
UDP-(1)fructose was synthesized essentially by the method of Michelson or Roseman et al. The product obtained was much more stable to acid than UDP-fructose isolated from Jerusalem artichoke tubers by Umemura et al.7) and UDP-glucose. Hydrolysis time curves of UDP-(1)fructose and fructose-1-phosphate in 0.01N HGl and 0.1N HCl both at 100°C are presented. It was concluded from these curves that UDP-(1)fructose was first hydrolyzed into UMP and fructose-1-phosphate, and then fructose-1-phosphate was hydrolyzed more slowly into free fructose and inorganic phosphate. 相似文献
123.
Hajime Taniguchi Yasukiyo Umemura Michinori Nakamura 《Bioscience, biotechnology, and biochemistry》2013,77(2):231-239
The acid-soluble nucleotides were extracted from the tubers of Jerusalem artichoke with percbloric acid, and separated and purified by means of adsorption on and elution from active charcoal, repeated chromatography on columns of Dowex I (Cl-), followed by paper chromatography. The following nucleotides have been characterized and/or identified: 5′-AMP, 3′-AMP, ADP, ATP, 5′-GMP, 2′-GMP, 3′-GMP, 2′,3′-cyclic GMP, GDP, GTP, 5′-UMP, UDP, UTP, NADP, UDP-glucose, UDP-galactose, UDP-fructose, UDP-N-acetylhexosamine and GDP-mannose.** Neither cytosine ribonucleotides nor deoxyribonucleotides have been detected. The significance of these observations is discussed. 相似文献
124.
Yoshimasa Taniguchi Yasuko Matsukura Harumi Taniguchi Hideki Koizumi Mikio Katayama 《Bioscience, biotechnology, and biochemistry》2013,77(10):1684-1694
The bitter acids in hops (Humulus lupulus L.) and beer, such as α-, β-, and iso-α-acids, are known to affect beer quality and display various physiological effects. However, these compounds readily oxidize, and the effect of the oxides on the properties of beer or their potential health benefits are not well understood. In this study, we developed a simple preparative method for the bitter acid oxide fraction derived from hops and designated the constituents as matured hop bitter acids (MHBA). HPLC-PDA-ESI/HRMS and MS2 revealed that MHBA are primarily composed of α-acid-derived oxides, which possess a common β-tricarbonyl moiety in their structures similar to α-, β-, and iso-α-acids. We also developed a quantitative analytical method of whole MHBA by HPLC, which showed high precision and reproducibility. Using our newly developed method, the concentration of whole MHBA in several commercial beers was evaluated. Our results will promote the study of bitter acid oxides. 相似文献
125.
Mitsutoshi Nakamura Kenjiroo Matsumoto Yuta Iwamoto Takeshi Muguruma Naotaka Nakazawa Ryo Hatori Kiichiro Taniguchi Reo Maeda Kenji Matsuno 《Mechanisms of development》2013,130(2-3):169-180
Animals often show left–right (LR) asymmetry in their body structures. In some vertebrates, the mechanisms underlying LR symmetry breaking and the subsequent signals responsible for LR asymmetric development are well understood. However, in invertebrates, the molecular bases of these processes are largely unknown. Therefore, we have been studying the genetic pathway of LR asymmetric development in Drosophila. The embryonic gut is the first organ that shows directional LR asymmetry during Drosophila development. We performed a genetic screen to identify mutations affecting LR asymmetric development of the embryonic gut. From this screen, we isolated pebble (pbl), which encodes a homolog of a mammalian RhoGEF, Ect2. The laterality of the hindgut was randomized in embryos homozygous for a null mutant of pbl. Pbl is a multi-functional protein required for cytokinesis and the epithelial-to-mesenchymal transition in Drosophila. Consistent with Pbl’s role in cytokinesis, we found reduced numbers of cells in the hindgut epithelium in pbl homozygous embryos. The specific expression of pbl in the hindgut epithelium, but not in other tissues, rescued the LR defects and reduced cell number in embryonic pbl homozygotes. Embryos homozygous for string (stg), a mutant that reduces cell number through a different mechanism, also showed LR defects of the hindgut. However, the reduction in cell number in the pbl mutants was not accompanied by defects in the specification of hindgut epithelial tissues or their integrity. Based on these results, we speculate that the reduction in cell number may be one reason for the LR asymmetry defect of the pbl hindgut, although we cannot exclude contributions from other functions of Pbl, including regulation of the actin cytoskeleton through its RhoGEF activity. 相似文献
126.
Yuichi Kano Yôichi Kawaguchi Tomomi Yamashita Tsuneo Sekijima Yukihiro Shimatani Yoshinori Taniguchi 《Landscape and Ecological Engineering》2013,9(2):281-287
We validated the effects of a passive integrated transponder (PIT) tagging process on the oriental weather loach Misgurnus anguillicaudatus. Laboratory experiments were conducted to assess the effects of PIT tagging on fish survival, growth, wound healing, and tag omission. Two tagging protocols, standard syringe injection versus insertion through a small hole pierced by a fine needle-shaped awl, were compared using a 12.5 × 2.07 mm2 tag. A control group was also included. In comparison with the awl technique, syringe injection heightened the mortality of the loach and delayed healing of the wound caused by tag insertion. No effects of either PIT tagging method were detected on the growth of surviving loach. We also field-tested similarly tagged populations within a river-based irrigation system of Sado Island, Japan. Two different sized tags (long, 12.5 × 2.07 mm2; short, 8.5 × 2.12 mm2) were compared by using antenna loggers which detected fish movement through gates and automatically logged tagged fish’s tag IDs and timestamps. By comparing logged data and actual fish collection surveys both below and above the gates, 77% and 30% of actual loach movements were confirmed to have been successfully logged for the long and short tags, respectively. The awl insertion technique with the longer tag is therefore recommended for use in similar studies of smaller fish species. 相似文献
127.
Noriyoshi Watanabe Satoshi Morimoto Takeo Fujiwara Tomo Suzuki Kosuke Taniguchi Takashi Ando Tadashi Kimura Haruhiko Sago Atsuhiro Ichihara 《PloS one》2013,8(3)
Objective
The (pro)renin receptor [(P)RR] has been recognized as a multifunctional receptor. The purpose of this study was to assess the association between plasma soluble (P)RR [s(P)RR] concentration in human cord blood (i.e., neonatal blood at birth) and small for gestational age (SGA) birth.Methods
Participants were women with a singleton pregnancy who delivered at the National Center for Child Health and Development between January 2010 and December 2011. Inclusion criteria were availability of maternal pre-pregnancy and paternal body mass index, and the absence of structural anomalies in neonates. s(P)RR concentration in cord blood was measured in 621 neonates. The 621 pairs of mothers and neonates were categorized into four groups based on quartiles of s(P)RR concentrations in cord blood. SGA was defined as a birth weight below the 10th percentile for gestational age. Logistic regression analysis was performed to assess the association between cord plasma s(P)RR concentration (quartiles) and incidence of SGA births.Results
Among 621 neonates, 55 (8.9%) were diagnosed as SGA (SGA group) and 566 (91.1%) were not (non-SGA group). Average s(P)RR concentration in cord blood was 66.1±12.6 ng/ml (mean±standard deviation). There were 155 pairs in the first plasma s(P)RR concentration quartile (Q1: <58.2 ng/ml), 153 pairs in the second quartile (Q2: 58.2–65.1 ng/ml), 157 pairs in the third quartile (Q3: 65.1–73.1 ng/ml) and 156 pairs in the fourth quartile (Q4: >73.1 ng/ml). The distribution of SGA births was 18 (11.6%) in Q1, 14 (9.2%) in Q2, 16 (10.2%) in Q3 and 7 (4.5%) in Q4, respectively. The odds ratio of SGA births was 0.24 (95% confidence interval: 0.08–0.71) for the fourth quartile compared to the first quartile in multivariate models. The P-value for trend was also significant (P = 0.020).Conclusion
High s(P)RR concentration is associated with a lower SGA birth likelihood. 相似文献128.
Taku Watanabe Ichizo Tsujino Satoshi Konno Yoichi M. Ito Chisa Takashina Takahiro Sato Akira Isada Hiroshi Ohira Yoshinori Ohtsuka Yuma Fukutomi Hiroyuki Nakamura Yukio Kawagishi Chiharu Okada Nobuyuki Hizawa Masami Taniguchi Akira Akasawa Masaharu Nishimura 《PloS one》2016,11(3)
Objective
A positive association between the number of cigarettes smoked per day and obesity has been reported, whereas how other smoking-related indices, such as pack-years and duration of smoking, are related with obesity has been less investigated. We analyzed the age-adjusted cross-sectional association between smoking and obesity in a general Japanese population.Methods
We used data from a nationwide epidemiological study of Japanese adults (N = 23,106). We compared the prevalence of obesity (defined as body mass index ≥ 25kg/m2) among groups classified by smoking behavior, pack-years, number of cigarettes per day, duration of smoking, and duration and time of smoking cessation.Results
In men, current smokers had a lower odds ratio (OR) for obesity of 0.80 (95% confidence interval (CI): 0.72–0.88) compared to non-smokers, whereas past smokers had a higher OR of 1.23 (95% CI: 1.09–1.37) compared to current smokers. In women, there were no differences in obesity between the three groups classified by smoking behavior. However, in both sexes, the prevalence of obesity tended to increase with pack-years and the number of cigarettes per day, but not with duration of smoking in current and past smokers. Further, in male smokers, the risks for obesity were markedly higher in short-term heavy smokers compared with long-term light smokers, even with the same number of pack-years. Regarding the impact of smoking cessation, female past smokers who quit smoking at an age > 55-years had an elevated OR of 1.60 (95% CI:1.05–2.38) for obesity.Conclusions
In a general Japanese population, obesity is progressively associated with pack-years and number of cigarettes per day, but not with the duration of smoking. When investigating the association between obesity and cigarette smoking, the daily smoking burden and the duration of smoking require to be independently considered. 相似文献129.
Reducing Molecular Flexibility by Cyclization for Elucidation of Absolute Configuration by CD Calculations: Daurichromenic Acid 下载免费PDF全文
Circular dichroism (CD) calculations of flexible natural products have been difficult because of the large number of low‐energy conformers and ambiguous Boltzmann distributions. In this article, through electronic (ECD) and vibrational (VCD) studies on a natural product, (+)‐daurichromenic acid, we demonstrate that derivatization of a flexible molecule can dramatically reduce its flexibility. This work also shows the usefulness of derivatization for diminishing computational expenses required for optimization and CD calculations, and for increasing the reliability of the assignment of absolute configuration. Chirality 28:453–459, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
130.
Tohru Taniguchi Mai Asahata Akihito Nasu Yukatsu Shichibu Katsuaki Konishi Kenji Monde 《Chirality》2016,28(7):534-539
Separation of the diastereomers of glycosyl sulfoxides differing in the sulfur chirality has been difficult. This article presents a fast and scalable method for their diastereoseparation using a chiral stationary phase. The usefulness of this method was demonstrated in a 500‐mg scale separation within 20 min, and in the separation of trisaccharyl sulfoxide diastereomers. Chirality 28:534–539, 2016. © 2016 Wiley Periodicals, Inc. 相似文献